Airplane automatic pilot



June 11, 1940. s. G. CART-SON AIRPLANE AUTOMATIC PILOT Filed Feb. 26, 19:58

7 Sheets-Sheet 1 RATE OF mm mm BANK ATTORNEY B. G. CARLSQN AIRPLANE AUTOMATIC PILOT June 11, 1940.

Filed Feb. 26, 1938 7 Sheets Sheet 2 INVENTOR BER-T G C use" 1 H 51 ATTORNEY linllilfiii June 1940. B. a. CARLSON AIRPLANE AUTOMATIC PILOT 7 Sheets-Shget 5 Filed Feb. 26. 1938 J /7 INVENTOR Bgnr 6.60 son W0 NEY June 11, a. s. CARLSON KIRPLANE AUTCIIATIC PILOT Filed Feb. 26, 1938 7 Sheets-Sheet 4 INVENTOR WMRNEY 1 June 11, 1940. ,5, G, CARLSON 2,203,671

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0 control pendulum.

Patented June 11, i 1

, 2,203,671 AIRPLANE AUTOLIATIO PILOT Bert G. Carlson, Freeport, N. Y., assignor to Sperry Gyroscope Company. Inc., Brooklyn. N. Y., a corporation of New York Application February 26, 1938, Serial No. 192,717

9 Claims. (Cl. 244-76) This invention relates to automatic pilots for barometric control governing the rates of climb aircraft. In the present design of automatic or dive. pilots, the control instruments and valves are Fig. 13A is a sectionai view of the shaft placed on the instrument panel, but owing to the couplings at the control box controlling turn and crowded condition of the panel, I propose in the rate of turn.

UNITED STATES PATENT OFFICE invention .to remove these instruments from the ,,1Fig. i4 is a vertical section through the case of panel and place them in any convenient place Fig. 13. on the craft and operate the same by remote Fig. 15 is a side elevation of the variable speed control from a small control board ,on the instrurate of-turn device shown in Fig. 8. v

ment panel. This control board may contain Fig. 16 is a sectionaldetail of one of the relay no nothing but the several control knobs for governvalves and connections.

ing the rudder, ailerons and elevator through the Fig. 17 is a vertical sectiomthrough a portion automatic pilot and for governing the automatic of the pick-off controls at the directional gyro banking and the rate of turn or rate of climb. scope.

The indications of the gyroscopes used in the The gyro instruments may be similar to those m pilot may be repeated or not, as desired, on the at present employed, namely, the artificial horipanel, but I prefer to place on the panel only zon or 'gyro vertical I (Figs. 5 and 6) and direcsmall indicators showing the relative positions tional gyro 2 (Figs. 5, 7 and 17), the system of the three air nozzles, namely, the rudder, being in general similar to'that shown in the ailerons and elevator with respect to the gyros. prior patent of EA. Sperry, B. G. Carlson and m These indicators are used in synchronizing the C M. F. Bates, #1992370, dated March 5, 1935. control before engaging the pilot. These instruments, however, may be made sim- Referring tothe drawings,illustrating one form 'pler than at present employed, since no indicathe invention may assume, tors need be provided thereon as they are not Fig. 1 is a front elevation of the small control visible to the observer. The control box or boxes hon adapted to be placed on the instrument 3 containing the same maybe placed at any. panel. '3: convenient location on the craft, while the control Fig. 2 loan elevation, partly in section, of the panel 4 (Figs. 1- and 5) may alone be placed same with the front plate removed. on the instrument board. In Fig. 5, the panel Fig. 3 is a transverse section taken approxiis viewed from the back to show the several con- 9 mately on broken line 3-3 of Fig. 2', looking in nections running to the control box. the direction of the arrows. The control panel is shown as comprising essen- Fig. 4 is a vertical section taken approxitially a plurality of knobs 5, 6 and l by which mately on broken line 44 of .F'ig'. 2, looking in the rudder, ailerons and elevator may be man- Flg. 5 is a diagrammatlc'view of the automatic For this purpose there'is shown a flexible shaft pilot, showing the connections running between a 8 running from the shaft 5' of knob 5 to the the control panel and the control box. directional gyro 2 to alter the relation between Fig. 6 is a plan view of the artificial horizon the follow-up controller thereat and the air- M portion of the control box, with the cover partly plane for changing course through a predeterw broken away. mined angle. The shaft 8 is shown as coupled Fig. 6A is a detail face view of the gear drive to shaft 8 journaled in box 3 and geared through between two shafts entering the gyro box, with worm! and worm wheel Ill which operates the small cover plate removed. through a differential II to change the. position Fig. 7 is a plan view, partly in section. of the of the pick-oil ports II, at the gyroscope iFlg. 5 directional gyro portion of the control box. 17), which ports turn with large gear llll mesh- Fig. 8 is a detail of the turbine drive for the ing with gear ill turned from a second arm of variable speed gear. differential lfl.

Fla- 9 is a face view of the at c banking A flexible shaft 15 runs, from the shaft 6' of knob i to enter theartiflcial horizon gyrocasing 5o Fig. 10 is a. vertical section of the same. at coupling It to drive shaft l8 which alters the Fig.11 is a vertical section ofv the same taken position of ,the banking pick-oil's and, 80' at at right angles to Fig 10. this gyroscope through pinion H2, differential Fig. 12 is a rear elevation of the pendulum. l5l, pinion I52. and large gear sector 3 to Fig. 13 is an elevation, partly in section, of,the I control the ailerons. Similarly, a flexible shaft 55 I parts, the former having a downwardly extend-- ing thumb piece 2i and a main knob It for the rate of turn. The latter is mounted on shaft it which is coupled to flexible shaft M leading to the gyro box (Fig. 13A) where it is coupled to shaft as, hereinafter described. The thumb piece ii is shown as mounted on a sleeve 22 having thereona gear 23 meshing with. a gear 24, the shaft 2d of which is connected to the shaft 25 which runs to the directional gyro box and operates, through gears H4 and iii (Figs. 7 and 13A), a reversing intake air sleeve valve 82 (Fig. 13A) to control the direction of rotation of the reversible air turbine wheel 26 by controlling the flow of air through pipes 21 and 28 to thenozzles 29, .30. The turbine wheels drive through shaft 3], reduction gears 32, worm 8 3 and worm wheel 34, a disc on the shaft 88 of theworm wheel.v

Frictionally engaging said disc is a. miller is which is radially adjustable across the face of the disc by being splined on shaft 38. The roller is shown as having an extension sleeve 89secured thereto,

. having circular teeth or grooves 88' therein with which meshesa pinion on shaft 4i (Fig. 15).

' As stated above, said shaft is connected through suitable couplings and flexible shaft it" to the knob It, by which the rate of turn may be set in by varying-the position of the roller on the roller. The shaft 38 of the disc drives through skew gears 42 the same. worm. gear 9 that is turned from shaft 8, so that the turn is eifected in this manner at a predetermined rate. The third arm of differential II is driven from the follow up pulley 85 through shaft 86',*worm 81 and worm wheel 88.

The opposite knob 20 for the rate of climb likewise has an auxiliary thumb piece 48 by which the automatic climb may be turned on or; on. The construction of the thumb piece may be the same as that of thumb piece 2 I it turning a sleeve- 89 to turn through gears 88 and SI shaft 48',

. which in turn drives through gears 82 and 88 at the box 41 asleeve 48 entering the box 41 containing the barometric device 48 of the aneroid type. Said sleeve is shown as having a forked member 49 secured thereto which is engaged by a pin 50 secured to the shaft 5i so that said shaft is rocked as the sleeve is turned, to open and close the ports in valve I I6 connected to the turbine 52 through pipes 86"and 91' governing the climb and dive of the craft. The rate of climb is governed from the shaft 53, on which is mounted the pinion 54 meshing with a gear 58 on the threaded stem of the needle valve, 56 to regulate the amount of opening of they valve, a flexible extension of the shaft 53 extending back to the instrumerit board and being connected to the shaft 20' of theaforesaid knob 20.

The barometer 48 is shown as temperature pivotallyhaving a capillary leak to the atmosphere, in my present invention I combine the advantages of both types, since my needle valve may be either wide open, closed tightly, or opened a very small amount, so that my device may operate either as a sensitive barometer or as a variometer, at the will of the aviator. All of this may be effected merely by adjusting the knobs 2t and 83 on the instrument panel. To this end, the knob 29) is provided with a small pointer Q28 reading on a scale E22, so that a definite rate of climb (or descent) may beset on the dial. It is interesting to note that the pointer i2I is set in the same position whether the airplane be climbing or diving, since it merely varies the rate of change of barometric pressure above which the automatic pilot comes'into operation and prevents any greater rate of change.

In taking off. for instance, the aviator would first leave the needle valve wide open until he gets fairly into the air. He then may almost close it, leaving a minute opening, so that the air plane would ascend at a predetermined rate with the knob I set for ascent. After reaching the desired altitude, the needle valve would be closed so that the barometer would act as a true barometer to maintain the plane at that height. When it is desired to descend, the aviator may set knob 1 for descent and open the needle valve slightly so that he may descend at a predetermined rate. This has a great advantage in blind landings,

since upon receiving the signal to descend, the

. the elevator, so that a throttle control could be provided in addition to or instead of the elevator control, if so desired, to increase the engine speed for ascent and decrease it for descent.

An automatic bank knob I8 is connected to.

shaft 58 to turn a shaft 59 within the horizon control box and having a pin 60 thereon engaged by the forked end of a rocker arm OI. (Figs. 9 to 12) Said arm is shown as mounted on a shaft 82 having a pin 88 at the inner end thereof engaging a notch 84 in a slldably mounted plate 85. Said plate has two holes 68 therein which, in one position, register with ports 61 in the casing 68, which supportsand encloses a small pendulum 69. In the osition shown in Fig. 11, however, the ports are c used to shut off the automatic bank control. The pendulum is shown a pivoted on axis II. The ports i'l are normally b ted by a straight edge projection 85 on the back of pendulum 88 (Fig. 12) and lead to the automatic'bank turbin'e 'lI through pipes 96 and 81. Preferably, paddles or blades I2 are connected to one or both of the air turbines, at least to the elevator turbine toretard the same without interposing any resistance to starting and cause it to run at a uniform speed to give a uniform rate of climb or descent.

It is interesting to note that the auxiliary pendulum it performs an important function in maintaining level flight immediately after a turn. At, this time the gyro vertical I is usually, or

' may be, deflected from the vertical several de- 1 grees through the action of the lateral accelera tion forces during the turn on the erection device, so that without the pendulum 69, the airplane would fly with one wing down until the of the pick-off ports 80 and 80 will be corrected As the so that the airplane will fly horizontal. gyro straightens up, the signal from the pendulum 69 decreases simultaneously, so that level flight is maintained. .Therefore the knob I9 is preferably left in the "on position most of the time, whether flying straight or turning.

Similarly, the barometric means acts to prevent the plane assuming a wrong attitude in case the gyro vertical becomes deflected in a fore and aft direction, for instance, after a marked change in speed; If the gyro vertical is so deflected, the airplane will start to climb or dive, resulting in a change in barometric pressure which results in operation of the barometric pick-oil" to move the turbine 52 to shift the positions of the pickofis at the gyro through the differential I50.

Preferably, answer back indicators are provided on the panel, these being shown in the form a of simple pointers i4, l5 and, one for each of the rudder, ailerons and elevator, and which are moved left or right according as air nozzles and gyros are not synchronized. The pointers are shown as pivoted to the panel at H, H and Ti, and are centralized by. springs it connected to a U-shaped bend at the lower ends. Since all three pointers are similarly arranged only the answer back system'associated with the rudder will be described. Also pivoted thereto is a downward extension 79 from a U-shaped member Hill which is connected at its outer ends to the piston rod Hll, connected to the diaphragm or movable wall )2 bisecting a chamber N13, to the two sides of which are connected pipes 1M and Hit leading back to pipe junction box connection i211 at the boxes Sand l. From there, the pipes lead to the two chambers on each side of the respective relay valves m5 which operate the pistons I06 of the oil control valve fill. Hence any differential air pressure in the relay valve will be reflected by a movement of the diaphragm it? to operate the proper pointers H, 15 or 16. It should be understood that the primary air impulses to chamber WE are transmitted through pipes i4 and it from the pick-off ports i3 and M at .the directional gyroscope or similar ports at the 5s" horizon gyroscope.

It is understood that the other two pairs of pipes Hit and Ni run to the elevator control valve and the aileron control valve in the same manner as the pipes HM and IM' are connected to the rudder control valve I01, so that the pointers i5 and it will show whether or not the re spective control valve and hence the respective servomotors have responded to the signals set in by the knobs on the panel.

The indicators i4, 15 and. 16 have an important. function in enabling the aviator to synchronize the pilot with the airplanes position before he throws in the automatic pilot. The present pracsition due to the fact that one of the turn, climb or bank knobs 5, 6 or I may have been left in a non-centralized position. After leveling off, the aviator first throws the air on the system and then brings the aforesaid knobs to the position where the pointers ll, 15 and 16 are centralized, at which time he knows that the positions of the pick-off ports at the gyroscope are centralized with respect to the gyro cut-off plates. The pilot may then be thrown in safely without disturbing the attitude of the plane.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departlngfrom the scope thereof,

it .is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim and desire to secure by Letters Patent is:

1. In an automatic pilot for aircraft, a plurality of control knobs at the instrument panel, remotely located master controlled instruments, means connecting said knobs and instruments .to change the attitude of the plane, fluid pressure relay valves thereat controlled by said instruments, and fluid pressure answer-back means from said relays to said panel adjacent said knobs.

3. An automatic pilot as claimed in claim 1,

having separate control knobs for putting in either a change of pitch attitude or a given rate of change of climb or dive, or both.

4. An automatic pilot as claimed in claim I, having separate knobs to bank the plane at will or to bank it at the proper angle during a turn.

5. In an automatic stabilizer for airplanes, having a control panel and a remotely located control box, a gyro vertical in the latter, pick-off means governed by the relative position of said gyroscope and airplane about a. fore and aft axis for positioning the ailerons, a pendulum also pivoted about a fore and aft axis, means responsive to the average position of the pendulum for i shifting the said pick-oif means to change the relation between gyroscope and airplane to cause automatic banking at the proper angle, and means for rendering said pendulum responsive at will from pilot omprising knobs for moving each of said' firstmentioned means,'knobs for operating each of said second ,mentioned means, and indicating means adjacent said knobs, controlled from the. automatic pilot, to assist in synchronizing the pilot with the crafts controlsurfaces before the pilot is thrown in.

'7. In an automatic pilot for aircraft, the combination with a course maintaining means, a rudder control device actuated therefrom for steering any predetermined course, a horizon gym and ailerons actuated therefrom, a servomotor for altering the relation between said means and rudder to cause turning, a variable speed drive between said motor and' said device to vary the rateof turn at will, a second serv'omotor foraltering the relation between said horizon gyro and 7 tit) eluding a course change knob, a rate of turn the ailerons, and a short period pendulum for actuating the second servomotor, whereby the aircraft maybe caused to turn at a predetermined rate without side slipping.

8. In an automatic pilot for aircraft. a plurality of control knobs at the instrument panel,

remotely located master controlled instruments,

flexible shafts connecting said knobs and instruments to change the attitude of the plane, fluid pressure relayvalves thereat controlled by said instruments, and fluid pressure answer-back means from said relays to said panel adjacent v said knobs. I i

9. In an automatic pilot for aircraft, a plurality of control knobs at the instrument panel mknob and an automatic bank knob, direction aeoaen maintaining means and attitude maintaining means for maintaining the course and attitude -of the plane, a variable speed servomotor for causing turns at predetermined rates through said direction maintaining means, an automatic bank device connected to said attitude maintaining means, means connecting said course change knob and said direction maintaining means for changing course by a predetermined amount, means connecting said rate of turn knob and said ser vo means for setting up a predetermined rate of turn, and means operated from said automatic bank knob for rendering operative and inoperative at will said automatic bank device.

- BERT G. caRLsoN. 

